This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1894 Excerpt: ...is greater near the poles than at the equator. And it is greater partly because the pendulum is then nearer the centre of the earth--nearer the point at which all the power of attraction can be considered to be concentrated. Since this is the case, all parts of the earth's surface are not at an equal distance from the ...
Read More
This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1894 Excerpt: ...is greater near the poles than at the equator. And it is greater partly because the pendulum is then nearer the centre of the earth--nearer the point at which all the power of attraction can be considered to be concentrated. Since this is the case, all parts of the earth's surface are not at an equal distance from the centre, in other words, the earth is not a perfect globe; it is a globe slightly flattened at the polar regions. The distance through the earth from pole to pole is thus less than that which separates two opposite points on the equator. As a matter of fact, the difference is nearly twenty-seven miles, for the distance through the earth at the poles is 7900 miles, while the diameter at the equator is nearly 7927 miles in length. On a globe 2 feet in diameter this difference would be represented by a little less than one-twelfth of an inch. To compare the earth with an orange leads, therefore, to a misconception as to the amount of polar compression, for if the earth were accurately represented by a ball of such a size, the departure from the globular form would be quite imperceptible. The diameter of the earth having been found, the extent of the surface can be easily calculated. It proves to be rather more than 197 millions of square miles. Of this vast area, the land surface consists of about 52 millions of miles, or 33,280 millions of acres. We have now come to a most important point, namely, the determination of the mass of the earth. But before going further, it is necessary to clearly define the meaning of mass. Suppose for a moment that we could fly away into a region of space far removed from the earth or any other body, taking with us a ball of.lead and a ball of cork, and placing them in this infinite ocean. The balls would remain for...
Read Less
